#!/usr/bin/perl

use strict;
use warnings;
use Math::Combinatorics;

my @zeichen = ('A'..'C');
my $count   = 3;
my %permute;

my $combo   = Math::Combinatorics->new( count => $count,
                                       data  => [(@zeichen) x $count]);

while(my @combo = $combo->next_combination){
   $permute{join(' ', @combo)} = 1;
}

print join "\n",keys %permute;